


gaze into the abyss

by plotholes_and_paradoxes



Series: When Fighting Monsters [1]
Category: Undertale (Video Game)
Genre: At Least Until The Sequel, Creepy Chara, Eventual Happy Ending, Everyone Has Issues, Everyone Needs A Hug, Frisk's Pronouns are They/Them, Genocide, Get Dunked On, Hurt/Comfort, I swear, Maybe - Freeform, We Don't Like Chara, also, chara possesses frisk, eventually, we'll see
Language: English
Status: In-Progress
Published: 2016-02-16
Updated: 2016-12-25
Packaged: 2018-05-20 23:23:37
Rating: Not Rated
Warnings: Major Character Death
Chapters: 6
Words: 3,247
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/6029347
Author URL: https://archiveofourown.org/users/plotholes_and_paradoxes/pseuds/plotholes_and_paradoxes
Summary: <blockquote class="userstuff">
              <p>In the battle against Sans, Frisk chooses Mercy.</p><p>And then they choose it again.</p><p>And again.</p><p>And then they always reset.</p><p>It didn't take a rocket scientist to figure out something was wrong. And Sans isn't one - he is a theoretical physicist. Close enough.</p>
            </blockquote>





	1. when a good man goes to war

**Author's Note:**

> “Beware that, when fighting monsters, you yourself do not become a monster... for when you gaze long into the abyss. The abyss gazes also into you.”  
> \- Friedrich Nietzsche

A pause.

One second.

Two seconds.

How many times had they been here before? How many times had he judged this demon for the same crime?

A shaking hand reached out. Silver covered to the hilt in dust clattered to the floor.

“You’re sparing me?” 

Sans gazed upon the child in front of him. He almost felt sorry for the murderer in his path. Their entire body shook with fear. They were afraid of him. And that felt good, even though he knew it shouldn’t. But this kid had caused him so much pain.

He could hear from where he was standing that their breathing had gone funny. But he couldn’t make himself feel all that bad because their sweater, their hair, their hands were caked with what he knew to be the dust of everyone he had ever cared about. 

Nevertheless he held his arms open – welcoming the demon.

“Finally. Buddy. Pal.”

They had taken a step forward, closer to his outstretched arms. They bit on their lower lip, and he could sense that they had doubts already on exactly how merciful he would be. He was glad. Because if Frisk knew they wouldn’t be spared and chose it anyway, they had to still have some humanity left deep inside themselves. 

But that wouldn’t be enough to save them.

“I know how hard it must be… to make that choice. To go back on everything you’ve worked up to.”

But they continued forward. 

“I want you to know… I won’t let it go to waste… c’mere pal.”

They threw themselves into his arms. He could feel their sobs ripping through their body as they leaned against him. If this were his Frisk and not a murderer who had ripped though the underground, through Papyrus, he would be worried about the fact that he could feel their ribs through their thin sweater. He would be worried about the fact that they were struggling to breathe in his grip, even if mercy hadn’t been his plan in the first place.

He held them close as he summoned the bones behind them. He pressed their eyes into the soft blue fabric of his hoodie. They may be a dirty brother killer, but the part of him that ached for the first go through told him there was no need for them to watch their death approaching. 

They let out a sharp gasp as the bones hit their target. They sunk to the ground, blood pooling around the tiles beneath them. 

As their HP drained, San knelt down.

“Get dunked on.”

Pushing himself up, Sans began walking out of the hall, only to be stopped by a small voice behind him.

“S-stay. Please.”

Standing still he stared at the small figure on the floor. They were drenched with their own blood, their HP dangerously low. 

“I-I’m scared of dying alone. Please d-don’t leave.”

Sans wanted to scream at them, tell them if they didn’t want to die alone they shouldn’t have killed his brother. But their soft whimpers reminded him too much of a time when he had actually believed their happy ending would last. If he wouldn’t do it for this Frisk, then he would force himself to do it for that Frisk.

He knelt down next to the child, absentmindedly noticing the blood seeping into his shorts. It wasn’t like it was going to matter when everything was reset.

He reached for their hand. Their eyes stared up at him, clouded with pain. Their eyes were different – they were their old brown instead of the read he had become accustom to. Hadn’t they used to be brown? On that good run?

“T-thank you S-Sans.” 

They smiled up at him as their HP hit zero. Their soul rose about them and shattered. Sans didn’t release his grip on their hand. He felt it grow cold and then dropped it. He dipped his head towards Frisk’s.

“If we’re really friends… you won’t come back.”


	2. where my demons hide

**Notes for the Chapter:**

> "No one wants to go into the darkness alone."  
> \- Jeyn Roberts, Dark Inside

Dodge. 

Dodge again.

Offer Mercy.

Show them exactly what your “Mercy” consisted of.

Hold their hand.

Watch as their soul shattered into tiny little fragments.

Wait for the reset.

It was an endless loop, a harsh unforgiving terrain of bones and dust and the crackling energy of the Gaster Blasters he summoned. 

The anomaly would cut down everyone in their path, eyes burning scarlet as their blood when it stained the floor and their lips and his clothes. But then they’d get to the hall of judgment and their eyes would return to chocolate and they take Mercy.

Every.

Single.

Time.

If Sans was going to be honest with himself, he might have admitted that sometimes he just wanted them to win so he could get a break for the 5 minutes before they reset.

But they wouldn’t even grant him that small mercy. 

Until one time as they walked forward, he asked the question that he knew he would eventually.

“Why are you still doing this?”

Frisk froze. That was new. It was something that had never been asked of them before. Sure, they knew he remembered bits and pieces of timelines – but there had been almost no change in script since they had first begged him to stay. Their eyebrows knitted together as they processed his question.

“Why do you keep killing everyone in your past to die over and over to the same thing? Why do you do this to everyone, over and over?”

The child swallowed painfully. Their eyes looked distinctly shiny as the knife in their hand wavered. 

Sans could have sworn that he had seen that hand shake when fighting Papyrus the last couple runs. But it didn’t stop them from cutting down Papyrus. And Undyne. And Mettaton. And even if they didn’t kill her with their own hands, Alphys. 

“It’s not my choice Sans.”

Their eyes pleaded with Sans to listen. But Sans wouldn’t accept that as an answer.

“I – I can’t control myself. I’m not in charge. Sans, please believe me. I know it sounds crazy! But – ”

Sans’s eye blazed bright blue as he summoned an attack behind Frisk. Frisk took a trembling step back at the sight of his eye blazing with magic as he drove the bone through their chest. Their back arched against the bones and they fell to the floor, red spots consuming their vision. 

“Can’t or won’t? We always have a choice Frisk – and what kind of choices have you been making?”

Sans turned away from the shaking child and walked to the doors. He could hear the feeble whimpers behind him as Frisk realized that he was leaving.

“No, come back please! Sans!”

They coughed behind him and he could almost picture the way their body was shaking with the effort and the blood trickling from their lips.

“Please Sans, come back! I-I’m scared Sans. I-I’m so s-scared.”

Part of him wanted to turn back and hold their hand as their life escaped them. But he refused, continuing until only echoes of sobs remained ringing in his ears.

“Don’t kill anyone next time kid and we’ll talk.”

**Notes for the Chapter:**

> Literally the most annoying thing is when I write entire paragraphs calling Frisk "she," because that's what I call them in my head. Then I have to go back and replace every single word!
> 
> (Could someone donate a little DETERMINATION in the comments please? I'm writing this as I go, and even though I know where it's going it's really tiring me out.)


	3. get the hell out of hell

**Summary for the Chapter:**

> In which Sans finally figures out "Hey! Maybe Frisk isn't the one killing everyone they love!"

**Notes for the Chapter:**

> "Bombs are falling, world is stalling  
> I'm still trying, why are we fighting  
> Words destroy us, bait and toy us  
> I still love you, do you love me too"  
> \- Simon Curtis, "How To Start A War"

Something changed.

After you do something over and over it gets hard not to notice small differences. Like the way that their hand didn’t shake once as they stabbed his brother to dust, and not even one tremor as they cut down Undyne.

Like the way the eyes that were turned on him were blazing crimson that stared right through him, as though he wasn’t even there. 

“Kid?”

He didn’t know why he asked it. This thing was the furthest from the first iteration of Frisk that he had a memory of meeting.

They raised the knife and dove at him.

He dodged. Of course he did. It wasn’t exactly a new thing.

“Let’s just get to the point.”

He summoned his attacks, and they dodged each one flawlessly. Like usual. 

He fought,

They dodged,

They swung,

They missed.

The cycle had a rhythm to it. It was more like an endless dance of death than anything else.

Everything went the same way it always did.

Until he “SPARED” them. 

Their hand didn’t unclasp the knife. They didn’t drop it and accept death. Instead they swung.

He dodged. He always did. And if he was able to, he always would.

As he shot off more bones aimed at their soul, he spoke.

“Frisk that was the spot where you accept Mercy and I kill you.”

They laughed. It was harsh and cold and not what he remembered from a fragment of an echo of a memory where they had almost cried with laughter with his bad woopee cushion joke.

“Oh Sans. Don’t you get it?”

They swung the knife at him. The knife caked with the dust of everyone he ever loved.

They smiled at him.

“Frisk isn’t home.”

He grabbed their soul and flung them into the walls of the corridor. 

He dropped them to the ground and they shoved a slice of pie into their mouth. Pie that Toriel had baked specially for them.

“What do you mean ‘Frisk isn’t home?’”

They dodged his next attack, laughing viciously. 

“I mean, Frisk isn’t in control right now. I am!”

They grunted in pain as his Blaster hit their arm. 

“If you’re not Frisk, who are you?”

Their smile widened.

“Finally asking the good questions! I am the demon that comes when you call its name! I am Chara Dreemur, and your precious Frisk had to try so hard to get control.”

Sans dodged, again. It really was all getting a bit old.

“And when they did finally wrestle control away, you killed them. Over and over and over! But then you left them when they died, and they didn’t have enough DETERMINATION to fight back!”

Sans sent bones propelling through their chest and stomach and arms. They smiled at him, their HP too high to be killed by something like that.

“And the best thing, Sans? When you kill me here, I’m going to hand control back over. And that’s how it’s going to go until I manage to kill you!”

Sans didn’t know what to do. He knew he needed to kill this thing, and it was becoming increasingly obvious that simply killing them wasn’t going to stop them for long. Especially not if Frisk was going to be the one dying instead of Chara.

“Thank you though. They’re usually screaming the whole run. But you found a way to shut them up.”

His eyes landed on their soul. It was dimmer than he had expected it to be. In fact, upon closer inspection, it looked as though there was a film covering it.

Maybe he could…

He dodged again as a knife came dangerously close to his face.

He threw his magic directly at the soul, trying to rip off the layer of what he could only assume to be Chara.

A scream from them proved that something was happening at least.

“What are you doing? WHAT ARE YOU DOING?”

He shoved more magic in the wedge that was starting to form between the Frisk’s soul and Chara. 

With a terrible snapping sound they fell to the ground. Sans stood his ground, trying to figure out what he had caused.

Then a shadow rose from Frisk. It had a jagged smile and red eyes and looked completely livid. 

“So you’re the thing that made Frisk do all this.”

It stared at him. He could feel the flame in his eye ignite into a burning blue.

“You’re gonna have a bad time.”

**Notes for the Chapter:**

> I'm so sorry about the lack of updates, but I promise I'll try to update more! I have good news though - I usually binge write fanfics and right now I have a couple one-shots I want to work on. 
> 
> Also, you see how this is part of a series? I have a sequel planned, and it's not exactly going to be happy-go-lucky but it's certainly going to be a little sweeter than this.


	4. sick of all this noise

**Summary for the Chapter:**

> Sans feels bad. It's hard not to when the person you've repeatedly killed is actually innocent. Oh yeah, he also deals with Chara.

**Notes for the Chapter:**

> "Goddamn right you should be scared of me,  
> Who is in control?"
> 
> -Halsey, "Control"

The shadow smiled, its eyes the burning red of Frisk’s blood when he spilled it. But it had never been Frisk that was really at fault here, he had realized.

Much, much too late.

“So Sans, how does it feel?”

Sans threw a bone attack at the shadow, but the darkness dissipated and reappeared once the magic had past.

“Do you enjoy knowing about all the times you’ve killed them? Especially when they had never done anything wrong.”

There was a sneer in Chara’s voice. Sans recognized the attempt to goad him into doing something he’d regret. 

But he would not kill Frisk.

Not again.

So as the shadow leered at him he summoned Gaster Blasters in a circle surrounding them. With energy Sans did not know he had within him he finally got rid of the evil that had been haunting this hall for far too long.

His steps echoed on the floor as he knelt next to Frisk. Their wounds were terrible, and their HP almost at zero.

But not quite.

Frisk was too banged up to pick up without causing pain. And that was not what Sans wanted to do to them - for once. 

Concentrating he used his magic to pick up Frisk, the blue glow washing them with warmth.

But Frisk’s eyes flied open. They whimpered and their breath caught in their throat as they stared at Sans in fear. Sans was dizzy with the realization that he had used magic like this in an attack. Frisk thought he was still trying to kill them.

“Shh Frisk it’s okay. I’m bringing you home, okay?”

Sans’s attempt at calming Frisk down seemed to work as they relaxed against the magic. Levitating them Sans took a shortcut back to P̶a̶p̶y̶r̶u̶s̶ a̶n̶d̶ his home. 

Opening the door he was faced with a decision. He could put Frisk in Papy’s room, but that option would probably cause more harm than good. And his room was probably not the best place for them…

Gently resting Frisk on the couch, Sans wondered exactly what he had gotten himself into.

**Notes for the Chapter:**

> HHAHHAHA you know how I started this during winter break and promised updates during spring break? Yeah I do too. Sorry about that. Haha. Plz don't kill me.


	5. i don't know when you'll break but it's gonna be soon

**Summary for the Chapter:**

> Sans gets Frisk home with little trouble - the problem is what happens next. 
> 
> (Warning: this chapter may be a little slow but the next two are going to be painful [sorry {not really}])

**Notes for the Chapter:**

> "You're as sharp as a knife  
> and you fit like a glove  
> That is no way to live  
> that is no way to love  
> Full of fear in your skin  
> and the weakness in giving in"  
> \- Ellie Goulding, "Salt Skin"

Sans didn’t know what to feel about the murderer sleeping in his living room.

Frisk was a mess, their face blotchy and nose running. They had grabbed onto him the night before and their shaking body was held to his for longer than he wanted to admit. Frisk was going to need a lot of help, and Sans thinks he might not be able to save them from their demons.

If only Papyrus was here, he kept Sans from sinking into the endless sea of depression - 

If Papyrus was here, this would not be a problem in the first place. But Papyrus is dead, and he will continue being dead until Frisk fixes their mistakes. 

But that’s not really fair - the mistakes are Chara’s. Yet and Frisk has to bear the blame. 

Sans walked into the living room. He had to confront Frisk at some point, and this was his house, damn it. 

Frisk was evidently awake. They were curled up on the old green couch, their back in the corner between the cushions and the armrest. Sans could hear their shuddering breaths from the hallway. 

Slowly, Sans walked towards them. Frisk flinched back, fear spreading from their glistening eyes to their huddled body, as though trying to sink further into themself. 

Sans sat beside them on the couch, feeling it dip beneath him. 

“Frisk, do you want to talk about this?”

Frisk violently shook their head, so hard that Sans had to wonder if human heads could fall off. From what he remembered of the loads, however, he didn’t suspect they could. Or at least not that easily.

“Frisk you do know we’re going to have to talk some point, right?”

A nod this time. Frisk didn’t look happy about it though.

“How about you go take a shower and I’ll get some food?”

Another nod, this one a bit less hesitant. 

“‘K pal. It’s down the hallway.”

Frisk got up out of their corner in a tangle of limbs and a stumble. Sans would have found it slightly endearing if Frisk’s shaking didn’t show him both how terrified and how cold they were. (A̶n̶d̶ ̶i̶f̶ ̶P̶a̶p̶y̶r̶u̶s̶ ̶h̶a̶d̶n̶’̶t̶ ̶b̶e̶e̶n̶ ̶t̶h̶a̶t̶ ̶c̶l̶u̶m̶s̶y̶ ̶a̶t̶ ̶F̶r̶i̶s̶k̶’̶s̶ ̶a̶g̶e̶.)

While Frisk futilely tried to wash away the sins of another, Sans got to work defrosting one of the thousands of plastic containers of spaghetti in the fridge. 

When Frisk left the bathroom Sans could tell something was wrong. Their skin was rubbed raw, the splotches shining a bright pink. Frisk’s eyes looked unfocused, and not in the possessed-by-demon-child way but the about-to-pass-out way. 

And bingo, Sans was right. Frisk’s eyes fluttered shut as they toppled over.

**Notes for the Chapter:**

> Not my best work, but I really hope to get the next couple chapters out this week. Then I can finally start the sequel I've had planned since last February!
> 
> Comments are welcomed <3


	6. all of this pain

**Summary for the Chapter:**

> I swore the other day  
> That I'd whisk you away  
> From all of this pain  
> From all of this pain in you  
> \- Koethe, "Price"

As the store of spaghetti heated up, Sans wondered how it had come to this. Frisk was supposed to be living happily with Toriel on the surface, not lying limp on his couch while he tried to figure out how to take care of a very, very broken human. 

If Frisk was only broken physically, he could fix that. Enough rest and monster food could undo most or all of the damage. But it was the psychological stuff that he was worried about. Frisk needed help, and Sans was the only one who could help them without starting the timeline over, as every monster was out for blood. But Frisk was terrified to be in the same room as Sans, which didn’t bode well with the whole “fix Frisk on his own” plan.

And after he managed to fix Frisk, if that was even possible, he needed to figure out a way to get Frisk back to the start of the timeline without re-merging their soul with Chara’s.

As Sans contemplated how to take care of a depressed human, he heard Frisk stir behind him. 

“Hey kid, go wash your hands alright? I heated up some food.”

Sans could see Frisk nod out of the corner of his eye and shuffle over to the bathroom. The water turned on and went on for a minute or two before it turned back off and Frisk shuffled back out, their hands covered by the dusty sleeves of their sweater.

“You’re gonna have you use your hands to eat kiddo.”

Frisk nodded and pushed their hands out of their sleeves. The skin was bright red. Sans grimaced at the dryness of their hand.

“Why did ya do that buddy?”

Frisk stared down at the table, shaking their head.

Sans cleared his throat, voice firmer and less questioning.

“Frisk I need to know why you did this.”

Frisk pulled their hands back under their sweater, disused voice cracking.

“The dust wouldn’t go away.”

Sans nodded slightly, words for once stuck in his throat. 

“I see kid. How’s about you eat a little food and then we got to bed, ‘kay?”

Frisk nodded shakily and used their hands that were still balled up in their sleeve to grab a fork and shove some spaghetti into their mouth. After a couple minutes of awkward silence, Sans got up and helped Frisk out of their chair. 

“Well, uh, g’night Frisk."

Frisk wandered over to the neon green couch t̶h̶a̶t̶ ̶h̶e̶ ̶a̶n̶d̶ ̶p̶a̶p̶y̶r̶u̶s̶ ̶w̶e̶r̶e̶ ̶g̶o̶i̶n̶g̶ ̶t̶o̶ ̶g̶e̶t̶ ̶r̶i̶d̶ ̶o̶f̶ and flopped down on it. 

With that goodnight, Sans went up to his room. His slumber, however, didn’t last long. 

He could hear Frisk get up and wander out of bed. Hoping they were going to go back to bed, he ignored it for around ten minutes. Sighing, he got up to go investigate. Hopefully Frisk had freaked out and frozen and nothing had gone terribly wrong. 

However, the sight of Frisk in the kitchen with one of the knives did not bode well for either of them.

Sans could feel his eye light up and Gaster Blaster faze into existence behind him. 

Someone was about to have a bad time.

**Notes for the Chapter:**

> I've said it before, but I'm probably going to finish this addition to the series this week and hopefully start the other part! :P


End file.
